Why Your API Contract Breaks in Production (And How to Fix It in the Spec)

The most expensive API bugs I've seen weren't implementation bugs. They were contract bugs — cases where the producer and consumer had different beliefs about what the API promised, and nobody wrote it down before the code was shipped. Here's the pattern: a team builds an endpoint, the frontend and backend agree on the behavior in a Slack thread or a meeting, and the implementation proceeds. Six months later, a field gets renamed as part of a "minor cleanup," a consumer breaks silently, and the